Catalytic steam gasification of pinewood and eucalyptus sawdust using reactive flash volatilization

• Lignocellulosic biomass gasified into tar free syngas for the first time over a single catalyst bed.
• Gasification required lower O/C and steam/C feed ratios compared to cellulose.
• Gasification efficiency was in order of Eucalyptus > Pinewood > Microcrystalline Cellulose, which followed the trend in ash content.

Catalytic steam gasification of cellulose using reactive flash volatilisation (RFV) has been proven as a promising approach for syngas production. However, using cellulose as feedstock is economically unfavourable. This paper investigates the production of syngas using RFV of pinewood and eucalyptus sawdust as feedstock. Experiments were conducted to evaluate the effects of catalyst promoters, carbon to oxygen ratio, carbon to steam ratio, feedstock type and ash contents on product yields (i.e. gas, tar and char) and product gas composition. High gasification efficiency and low char selectivity were observed in the pinewood RFV with Re-Ni and Rh-Ni catalysts, which can be explained by the catalysts high active metal substrate dispersion. Additionally, in comparison to cellulose, higher gasification efficiencies were also observed in the pinewood and eucalyptus RFV. This can be attributed to the effects resulted from higher amorphous structure of lignocellulosic biomass compared to microcrystalline cellulose, and the catalytic effects of alkali and alkaline earth metals (AAEM species) found in the lignocellulosic biomass ash. The catalytic effects o f AAEM species further reduced the coke deposition on the Ni catalysts, making the effect of noble metal promoter on the Ni catalysts less significant. The effects on product yields and gas composition from promoters, carbon to oxygen ratio and carbon to steam ratio were less pronounced.

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